1. Field of the Invention
The present invention relates to a coating film forming method, a coating material, releasing agent and a rubber material.
2. Description of the Related Art
As a method for mold-vulcanizing rubber in a production process of a tire or the like, it is ordinarily conducted that a bladder in a rubber-made bag shape is inserted inside raw material rubber before being mold-vulcanized and, then, while the raw material rubber is pressed against a metal mold by supplying a gas of high temperature and high pressure such as steam inside the bladder, such mold-vulcanization of the rubber is performed with heating and pressure.
In order to prevent the bladder from sticking to the raw material rubber to be mold-vulcanized, an art of previously forming a film of, for example, a releasing agent containing a silicone rubber, transition element metal powder and a solvent containing a halogenated hydrocarbon oil on a surface of the bladder to be used in a step of mold-vulcanizing the rubber is known (for example, see Japanese Patent Unexamined Publication JP-A-8-20029).
By forming a coating film compounded with the transition element metal power, the above-described related art firstly efficiently captures sulfur or a sulfur compound which causes to accelerate deterioration of a silicone film on the bladder, and suppresses deterioration of the coating film of the releasing agent, to thereby enhance durability of the coating film.
However, since the related art adopts a method in which the coating film is formed in a state of covering a surface of the rubber which constitutes the bladder, sufficient durability against various problems to be generated with expansion and contraction of the bladder, such as a peeling-off or a scratch as an external factor, can not be exhibited.